1. Field of the Invention
The present invention relates to wire line cutting apparatuses, and more particularly the present invention relates to a wire line cutter apparatus for severing a wire line in the event a down hole tool has been jammed within the bore hole.
2. General Background
In the operation of gas/oil wells, the use of a flexible wire line to lower various types of down hole tools into the well bore is very common. As an example, during the drilling and during the completion of an oil well, production logging apparatuses are run down into the well bore, via the use of a wire line, and having an electrical cable also for enabling the apparatus to achieve readouts while in the well bore, including such things as temperature and pressure surveys, and the placement and removal of production and controlled gas lift valves, etc. All of these apparatuses are lowered down into the bore with the use of a wire line, which is a flexible steel cable or the like, so that once the services or readouts are complete, under normal circumstances, the instrumentality is retrieved out of the bore hole. However, as often is the case, these instrumentalities become locked due to debris down the hole, or improper alignment of the bore. What is required at that point is a "fishing" tool which has to be lowered down into the hole to retrieve the readout apparatus.
In most cases, the down hole tool which is lowered at the end of the wire line, is adapted with some sort of retrieval means so that the "fishing" tool may grasp onto the upper end of the apparatus, and retrieve it up out of the bore hole. This is usually the case when the tool is stuck rather firmly into the hole. It would be unwise to try to exert undo pressure on the apparatus by pulling on the wire line from the rig floor, due to the fact that the wire line may snap at any point at sometimes 10 to 30,000 foot hole, and therefore result in thousands of feet of wire line being or dropping down into the bore hole and causing an even more severe problem. Therefore, in order to combat this eventuality, it is often times wise to sever the wire line at a point very close to the top portion of the down hole tool, and retrieve the wire line prior to retrieving the down tool with a "fishing" tool.
In the present state of the art, what is normally achieved is some sort of a cutter or the like would be slidably engaged to the wire line at the top of the bore hole, while the wire line is rather taut, and it would be allowed to slide down the cable with the use of gravity or the like. Several patents do teach the use of types of cutters and they are are follows:
U.S. Pat. No. 3,926,252 teaches the use of a cutting device for flexible line having a tubular body, a fixed blade member and a rotating blade member. The members are engagable into one another, and would be activated upon the striking of the tool by a separate "go devil" drop down the hole after the cutting portion has been placed in position.
U.S. Pat. No. 745,526 would teach the use of an apparatus for cutting rope, the apparatus being adopted for dropping into a hole or otherwise for severing the rope when it comes into contact with a stationary object.
U.S. Pat. No. 1,610,699 would teach the use of an apparatus for dropping into a hole or the like for severing a rope with movable blades when the apparatus strikes a stationary object.
U.S. Pat. No. 756,730 would teach the use of an apparatus also for dropping into the hole or the like for severing a wire line.
U.S. Pat. No. 692,816 would teach the use of an apparatus also for dropping down a bore or the like for severing a rope or cable when the apparatus strikes an object.
U.S. Pat. No. 969,571 would teach the use of a rotatable blade for severing a line as the apparatus is dropped in a hole and strikes a stationary object.
U.S. Pat. No. 978,577 would also teach the use of an apparatus for dropping down the hole, so that when the apparatus strikes an object, a pair of blades, which are mounted on a rotatable shaft, move into the line and sever it.
U.S. Pat. No. 3,073,388, which would comprise a body slidably inserted over the cable and a pivotally mounted blade which cooperates with the cutting head of the body to cut the cable on the top of the well tool. In this patent, the blade is actuated by an explosive charge fired by a timing mechanism.
None of the above patents as listed, would achieve the ends which are achievable with the present invention. Particularly in U.S. Pat. Nos. 3,073,388 and 3,926,252, the disadvantages are that the cutting portion of the apparatus is struck with considerable force, either by the explosive charge in the '388 patent or in the force of the "go devil" as it has travelled down the well hole in the 252 patent. In both of those cases, the energy imparted on the blade member would cause a great crushing of the cable prior to the completion of the cut.